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Test Code RBCS Relative B-Cell Subset Analysis Percentage, Blood

Useful For

Screening for humoral or combined immunodeficiencies, including common variable immunodeficiency (CVID), hyper IgM syndrome, among others, where B-cell subset distribution information is desired


Assessing B-cell subset reconstitution after hematopoietic cell (HCT) or bone marrow transplant


Assessing B-cell subset reconstitution following recovery of B cells after B-cell-depleting immunotherapy

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CVID CVID Confirmation Flow Panel Yes No

Testing Algorithm

This test should be ordered only when percentages (relative distribution of B cell subsets within the total B-cell population) are needed for the reportable B-cell subsets. If both percentages and absolute counts are needed for the reportable B-cell subsets, order IABCS / B-Cell Phenotyping Profile for Immunodeficiency and Immune Competence Assessment, Blood.

Method Name

Fluorescent Flow Cytometry

Reporting Name

Relative B Cell Subset Analysis %

Specimen Type

Whole Blood EDTA

Shipping Instructions

Specimens are required to be received in the laboratory on weekdays and by 4 p.m. on Friday. No weekend processing. Draw and package specimens as close to shipping time as possible. Ship specimens overnight.


It is recommended that specimens arrive within 24 hours of draw.

Necessary Information

Ordering physician's name and phone number are required.

Specimen Required

For serial monitoring, we recommend that specimen draws be performed at the same time of day.


Specimen Type: Whole blood

Container/Tube: Lavender top (EDTA)

Specimen Volume:

≤14 years: 4 mL

>14 years: 10 mL

Collection Instructions:

1. Send specimen in original tube. Do not aliquot.

2. Label specimen as blood for RBCS / Relative B Cell Subset Analysis Percentage.

Specimen Minimum Volume

≤14 years: 3 mL; >14 years: 5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated 48 hours PURPLE OR PINK TOP/EDTA

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject

Reference Values

The appropriate age-related reference values will be provided on the report.

Day(s) Performed

Monday through Friday

Report Available

3 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

86356 x7

LOINC Code Information

Test ID Test Order Name Order LOINC Value
RBCS Relative B Cell Subset Analysis % 90416-9


Result ID Test Result Name Result LOINC Value
BCD19 CD19+ % of total Lymphocytes 8117-4
BCD20 CD20+ % of total Lymphocytes 8119-0
BCD27 CD27+ % of CD19+ B Cells 89358-6
B27MD CD27+ IgM+ IgD+ % of CD19+ B Cells 89352-9
B27N CD27+ IgM- IgD- % of CD19+ B Cells 89350-3
B27M CD27+ IgM+ IgD- % of CD19+ B Cells 89348-7
BIGM IgM+ % of CD19+ B Cells 89346-1
B38MN CD38+ IgM- % of CD19+ B Cells 89344-6
B38MP CD38+ IgM+ % of CD19+ B Cells 89341-2
B21P CD21+ % of CD19+ B Cells 89356-0
B21N CD21- % of CD19+ B Cells 89355-2
RBCSI Interpretation 69048-7